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The mineralization mechanism responsible for the fossilization of archaeological textiles in close proximity to metal artifacts presents a sophisticated preservation process at both macro and micro levels. This study examines archaeological textiles dating from 2200 BC to AD 1900, sourced from three distinct archaeological sites. The focus is on understanding the microstructural degradation of fibers within a specific burial environment and the preservation achieved through mineralization. These archaeological fibers of archaeological textiles exhibit morphological preservation in the immediate vicinity of copper-based objects. Utilizing tools such as a digital camera, scanning electron microscopy with energy dispersive spectroscopy (SEM–EDS), high-resolution synchrotron-based microtomography (μCT), and enzyme-linked immunosorbent assay (ELISA), we examined fiber morphology, conducted elemental analysis, identified fiber types, and analyzed fiber characteristics. Our findings reveal the presence of smooth-surfaced wools and silks, fibers covered with calculi, and fiber impressions—all subjected to mineralization. These mineralized fibers can be categorized into three distinct stages of mineralization, each exhibiting varying carbon content. We inferred a correlation between mineralization rate and carbon content while also identifying mineralization density distribution on these textiles. Lastly, this study provides insights into the preservation states of textiles across three different mineralization stages, enriching our understanding of the deterioration of organic archaeological material. [ABSTRACT FROM AUTHOR]

In this study, Cu/Ni and Cu/Al multilayers, with individual layer thickness varying from 25 nm to 200 nm, and co-sputtered Cu-Ni and Cu-Al single layer films were deposited at room temperature via magnetron sputtering and further annealed from 100 °C to 300 °C. The mechanical and microstructural properties of the as-deposited and annealed samples were characterized by nanoindentation, x-ray diffraction, and scanning electron microscopy. Both multilayer systems exhibit an increase in hardness with increasing annealing temperature. However, the Cu/Ni system shows a gradual and moderate hardness increase (up to 30%) from room temperature to 300 °C, while the Cu/Al system displays a sharp hardness surge (~150%) between 125 °C and 200 °C. The co-sputtered Cu-Ni and Cu-Al samples consistently demonstrate higher hardness than their multilayered counterparts, albeit with distinctly different temperature dependence—the hardness of Cu-Ni increases with annealing temperature while Cu-Al maintains a constant high hardness throughout the entire temperature range. The distinct thermal strengthening mechanisms observed in the two metallic multilayer systems can be ascribed to the formation of solid solutions in Cu/Ni and the precipitation of intermetallic phases in Cu/Al. This study highlights the unique advantage of intermetallic strengthening in metallic multilayer systems. [ABSTRACT FROM AUTHOR]

To investigate the durability of cementitious materials under complex environmental conditions in Xinjiang, this study conducted durability tests on mortar specimens with different fly ash contents under dry/wet sulfate attack conditions, with standard curing and steam curing at 70 °C. The appearance loss and flexural and compressive strength variations in the specimens were analyzed, and an evolution model of the mortar strength under a dry/wet sulfate attack was established. Moreover, XRD and SEM techniques were used to characterize the erosion products and microstructure, and to explore the erosion resistance mechanism of fly ash cementitious materials. The results showed that, after 160 cycles of erosion, the flexural strength of the specimens decreased with the increase in the fly ash content. In the context of steam-cured mortar specimens, throughout the entire erosion period, specimens with a fly ash content of 45% exhibited the highest relative compressive strength. The established strength evolution model had a minimum determination coefficient of 0.879, indicating a good agreement between the model and experimental results. Microscopic research showed that fly ash would undergo a pozzolanic reaction under the action of sulfate and calcium hydroxide, which was beneficial to the improvement of the erosion resistance. As the fly ash content increased, the erosion products of the specimens gradually became dominated by gypsum. [ABSTRACT FROM AUTHOR]

Chinese Edison pearls, invented and produced in China by the Zhejiang Grace Pearl Jewelry Co., Ltd, are usually large and round with variable but attractive colors. Edison pearls have entered the jewelry market in 2011. However, the fine microstructural characteristics of these pearls remain largely unknown, particularly the thickness of the nacre and the spatial distributions of organic pigment in the nacre. Herein, using X-ray microradiography analysis, field-emission scanning electron microscopy, and Raman spectroscopy, we comprehensively investigated the internal fine-microstructural characteristics of typical colored Edison pearls. Our results indicated that Edison pearls have a typical core–shell structure, in which the core is the nucellus and the shell is the nacre. Average nacre thicknesses varied from 1.00 to 3.60 mm among specimens. Surprisingly, theoretical calculations showed that nacre accounted for about 50–90% of the whole pearl by volume. In addition, multiple prismatic or irregular structures, almost entirely composed of aragonite, coexisted in the nacre of some Edison pearls; one of these structures was closely adjacent to the nucleus. Interestingly, the average thickness of individual aragonite tablets in the nacre gradually decreased from the inner nacre (near the nucleus) to the outer nacre (near the pearl surface). Finally, the intensity ratios of the two peaks in the Raman spectra (I1124–1134/I1085) were non-uniform across nacre regions, and generally increased with distance from the nucleus. This pattern was directly attributed to variations in pigment content among nacre regions. Our results substantially increase our understanding of nacre biomineralization and the gemological characteristics of colored Edison pearls. More importantly, this study identified certain characteristics that can be used to identify color-treated Edison pearls. [ABSTRACT FROM AUTHOR]

Composite metals are promising materials displaying better properties than the sum of their counterpart. Herein, layered and layered gradient (heterogeneous) Zr/Ti materials are fabricated via rolling bonding and annealing. For comparison, Zr/Zr, Ti/Ti, and homogeneous Zr–Ti alloys are also fabricated. The microstructures are characterized using scanning electron microscopy and electron backscatter diffraction. Tensions, compressions and microhardness tests are performed to evaluate the mechanical properties of Zr/Ti materials. Layered Zr/Ti composite is composed of alternated Zr layer/interface layer/Ti layer, and chemical composition is gradient distributed in the interface layer. Layered gradient Zr/Ti alloy is composed of multi interface layers, showing periodic composition gradient. It is found that the strengths of the layered and layered gradient Zr/Ti materials decreased with the increase of layer thickness. The yield strength of the layered Zr/Ti composite is higher than the strength calculated with the rule of mixture (ROM), indicating extra strengthening. However, the yield strength of the layered gradient Zr/Ti alloy is lower than the calculated strength based on ROM. The effects of the layered and layered structures on the mechanical property of Zr/Ti materials are discussed. This study may provide a method to fabricate bulk heterostructured materials with gradient chemical composition. [ABSTRACT FROM AUTHOR]

In this report, two-dimensional (2D) bismuth selenide (Bi2Se3) nanosheets (NSs) and reduced graphene oxide (rGO) (Bi2Se3/rGO) composites have been prepared via a hydrothermal method. The microstructures and morphology properties of Bi2Se3/rGO composites were analyzed by scanning electron microscopy (SEM) and Raman spectra, indicating a well prepared and high crystalline material. Photoelectrochemical (PEC) tests demonstrate that Bi2Se3/rGO heterojunction exhibits enhanced photocatalytic performance of the pure Bi2Se3, which is about five times higher than Bi2Se3 NSs, which is because rGO acts as a conduction pathway, resulting in efficient separation of photogeneration of electron–hole pairs on the Bi2Se3/rGO composites. The as-prepared composite provides a novel insight in the field of photocatalysis. [ABSTRACT FROM AUTHOR]

Composite materials with inorganic nanoparticles were systematically investigated to prepare a highly functional composite. This study reports poly(acrylic acid) (PAA) and CaCO3 nanoparticle complexes (noted as PAA-CaCO3) that were layer-by-layer (LbL) assembled with poly(allylamine hydrochloride) (PAH) to produce (PAH/PAA-CaCO3)*n adhesive films with n deposition layers of PAH/PAA-CaCO3(n is the number of deposition cycles). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrated that CaCO3 nanoparticles were homogeneously dispersed in (PAH/PAA-CaCO3)*n adhesive films. Polyelectrolytes repeat the "in-and-out" diffusion processes in adhesive films by exponentially growing the LbL assembly, which well disperses CaCO3 nanoparticles. Adhesive films exhibited high adhesive strength, even reaching 3.76 ± 0.67 MPa when the content of the CaCO3 nanoparticles reached 70 mol%. The results demonstrated sufficient adhesion performance for use as an adhesive in advanced optical applications. Optical transmittances of adhesive films were all greater than 87% in the visible light range. Furthermore, the refractive index (RI) increased from 1.5332 to 1.5450 with increasing CaCO3 nanoparticles content. [ABSTRACT FROM AUTHOR]

The purpose of this study was to combine polydioxanone and concentrated growth factor extracts to enhance the stimulation of fibroblast collagen synthesis by polydioxanone in facial plastic. In this experiment, polydioxanone was prepared as a nanoscale bioresorbable scaffold by electrospinning. The PDO-CGF mat was prepared by loading the concentrated growth factor extract onto the polydioxanone mat by lyophilization after soaking. The diameter of the mat fibers was observed by scanning electron microscopy, and the mechanical properties, biocompatibility and cytotoxicity of the material were analyzed. The release rate of transforming growth factor-beat1 (TGF-β1) in the PDO-CGF mat was evaluated by enzyme-linked immunosorbent assay (ELISA), and the amount of collagen synthesis was evaluated by real-time polymerase chain reaction (RT-PCR) and immunofluorescence. The results showed that the PDO-CGF mat had a nanometer-scale fiber diameter and an elastic modulus similar to skin and was able to pull during cell contraction. The PDO-CGF mat showed good biocompatibility, and the appropriate concentration of the PDO-CGF mat can significantly promote cell proliferation. ELISA showed that the PDO-CGF mat stably and continuously released TGF-β1. RT-PCR and immunofluorescence staining showed that the PDO-CGF mat stimulated fibroblasts to synthesize type I and type III collagen. These results indicate that a suitable concentration of the PDO-CGF mat can better promote the synthesis of collagen by fibroblasts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydrophobic proppants are fabricated. • Wettability is tunable and control-released. • Meet high demands in oil/gas exploitation. Ultra-low-density proppants with tunable and control-released hydrophobicity can meet different requirements of different fracture environments, thus playing an important role in unconventional reservoir exploration. In this study, for the first time, we designed and synthesized proppants with a molecular structure of γ-methacryloxypropyltrimethoxysilane (KH570)-styrene (St)-divinyl benzene (DVB) (FR-SDB) through suspension polymerization. FR-SDB was examined by Fourier-transform infrared spectroscopy, atomic force microscopy, scanning electron microscopy, and X-ray diffraction to understand the mechanism of tunable and control-released hydrophobicity. The results revealed that the hydrophobicity is related to the hydration reaction of chemically bonded KH570 and the difference in the reaction activities under different aqueous environments at different temperatures. The wettability of FR-SDB was evaluated according to the static water contact angle (θw) on its surface. The contact angle θw on the surface of FR-SDB can be tailored from the initial angle of approximately 50° to 80°–125° in a wide time range of 10 min to 144 h. FR-SDB exhibited ultra-low apparent density of approximately 1.028 g/cm3, high compressive strength, and a crushing ratio of ∼ 1.81% at closure pressure of 69 MPa. [ABSTRACT FROM AUTHOR]

Amphorotia is a diatom genus of considerable morphological and biogeographical significance. It was established by transferring several Eunotia species and describing several new species. The most species were found dispersed towards Southeast Asia. In coastal areas of China, a number of species of Amphorotia were found and the assemblages contained several new taxa. This article provides additional information on five previously described species and describes one new species, Amphorotia zhujiangensis sp. nov., and one uncertain but special species, A. sp. These are based on fossil material from a deltaic borehole, subaquatic sediment cores and surface sediments collected in the Pearl River estuary region. Morphological data were derived from light and scanning electron microscopy. A detailed morphological comparison of seven Amphorotia species is included, indicating the existence of a diverse group in brackish waters. Relationships within the family Eunotiaceae are briefly discussed. The biogeographical range of regional habitats occupied by Amphorotia species in tropical Southeast Asia is also expanded. [ABSTRACT FROM AUTHOR]

The composite of organic and inorganic phases is a promising design to create higher performance cement-based materials. In this work, with aniline monomers mixed with synthetic calcium silicate hydrate (C–S–H) gels and then in-situ polymerized, we investigated the influence of this organic modification on the structure and mechanical properties of C–S–H with different calcium to silicon ratios (C/S). Scanning electron microscopy (SEM) images and nano indentation results show the addition of aniline lowers the packing density of C–S–H particles with C/S = 0.7 at meso-scale, and thus causes a substantial fall in the indentation modulus. However, the slower creep rate of C–S–H/aniline indicates aniline monomers may situate in the midst among particles to obstruct the translation between neighboring calcium silicate sheets. For C–S–H samples with C/S = 1, the organic modification occurs at a smaller length scale. X-ray diffraction (XRD) spectra suggest the relatively ordered packing of (0 0 2) crystal plane is strongly disturbed by the incorporation and in-situ polymerization of aniline monomers. Nuclear magnetic resonance (NMR) patterns also prove a nano-structural reorganization of silicate tetrahedra takes place in C–S–H/polyaniline. The interaction mechanisms interpreted here may give solutions to enhancing properties of civil engineering materials by organic modification. [ABSTRACT FROM AUTHOR]

To conduct research into the long-term preservation of fragile wool textile relics unearthed at archeological sites, it is essential to simulate the aging process and evaluate the factors affecting the degradation of wool fabrics. An accelerated aging method is therefore proposed to simulate the degradation process using either CaCl2 or NaCl in conjunction with hydrothermal treatment. The accelerated aging of wool fabrics was investigated by color measurement, scanning electron microscopy, cross-sectional observation, attenuated total reflection Fourier transform infrared spectroscopy, and amino acid analysis. Wool fabrics subjected to NaCl-hydrothermal or CaCl2-hydrothermal treatment exhibit an apparent yellowing with increasing treatment time. Fluctuations of cysteic acid and cystine dioxide content are shown to be the most prominent, and a distinct conversion of α-helices into β-sheets is observed with increasing treatment time. These results indicate that the effect of Ca2+ was greater than Na+ in promoting the degradation of disulfide groups in the hydrothermal degradation process. [ABSTRACT FROM AUTHOR]

Phospholipid complex is one of the most successful approaches for enhancing oral bioavailability of poorly absorbed plant constituents. But the sticky property of phospholipids results in an unsatisfactory dissolution of drugs. In this study, a matrix dispersion of baicalein based on phospholipid complex (BaPC-MD) was first prepared by a discontinuous solvent evaporation method, in which polyvinylpyrrolidone-K30 (PVP-K30) was employed for improving the dispersibility of baicalein phospholipid complex (BaPC) and increasing dissolution of baicalein. The combination ratio of baicalein and phospholipids in BaPC-MD was 99.39% and baicalein was still in a complete complex state with phospholipid in BaPC-MD. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier Transform Infrared (FTIR) analyzes demonstrated that baicalein was fully transformed to an amorphous state in BaPC-MD and phospholipid complex formed. The water-solubility andn-octanol solubility of baicalein in BaPC-MD significantly increased compared with those of pure baicalein. Compared with baicalein and BaPC, the cumulative dissolution of BaPC-MD at 120 min increased 2.77- and 1.23-fold, respectively.In vitropermeability study in Caco-2 cells indicated that the permeability of BaPC-MD was remarkably higher than those of baicalein and BaPC. Pharmacokinetic study showed that the averageCmaxof BaPC-MD was significantly increased compared to baicalein and BaPC. AUC0–14 hof BaPC-MD was 5.01- and 1.91-fold of baicalein and BaPC, respectively. The novel BaPC-MD significantly enhanced the oral bioavailability of baicalein by improving the dissolution and permeability of baicalein without destroying the complexation state of baicalein and phospholipids. The current drug delivery system provided an optimal strategy to significantly enhance oral bioavailability for poorly water-soluble drugs. [ABSTRACT FROM AUTHOR]

A monolithic nanoporous silver catalyst is developed to achieve a better performance than platinum at very low overpotentials for oxygen reduction reaction in alkaline conditions. Benefiting from the reaction‐promoting electrode architecture and the enhanced surface area, such a nanoporous silver catalyst exhibits a threefold improved overall activity compared to that of commercial state‐of‐the‐art platinum carbon catalysts at 0.90 V versus RHE. [ABSTRACT FROM AUTHOR]

Abstract: Hollow mesoporous tungsten trioxide microsphere (HMTTS) was synthesized by spay drying method and Pt/HMTTS were prepared and used as new electrocatalyst for methanol oxidation. The structure of HMTTS and Pt/HMTTS was characterized with scanning electron microscopy (SEM), tunnel electron microscopy (TEM) and X-ray diffraction (XRD), and its electrocatalytic activity toward methanol oxidation was investigated with cyclic voltammetry (CV) and chronoamperometry (CA). The characterizations from SEM, TEM and XRD show that the platinum particles with an average size of 5nm have been successfully distributed on the surface of HMTTS. Cyclic voltammetry and chronoamperometry indicate that Pt/HMTTS catalyst exhibits higher electrocatalytic activity and good stability during methanol oxidation in comparison to Pt/C and Pt/WO3 catalysts. [Copyright &y& Elsevier]

A resistance type organic vapour sensor was fabricated by porous silicon (PS) which was obtained by double-cell electrochemistry etching of p-silicon. PS was modified using copper (Cu) and silver (Ag) ions by electroless deposition. The surface morphology of modified PS was characterized by scanning electron microscopy (SEM). The sensing properties of Cu/PS and Ag/PS were tested, respectively. It is found that the Cu/PS has a similar sensitive ability to the formaldehyde, ammonia and ethanol at a low concentration range. However, the selectivity is very poor. Ag/PS is selectively sensitive to formaldehyde in a wide concentration range, for 5000 ppm, the sensitivity reaches 11.5. [ABSTRACT FROM AUTHOR]

A periodic-layered structure was observed in solid-(Cr, Fe)2B/liquid-Al diffusion couple at 750 °C. The interface morphology, the reaction products, and the potential formation mechanism of this periodic-layered structure were investigated using an electron probe microanalyzer (EPMA), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and energy-dispersive spectroscopy (EDS). The results indicate that the reaction between (Cr, Fe)2B and liquid Al is a diffusion-controlled process. The formation of intermetallics involves both the superficial dissolution of Fe and Cr atoms and the inward diffusion of Al at the interface. The layered structure, as characterized by various experimental techniques, is alternated by a single FeAl3 layer and a (FeAl3 + Cr3AlB4) dual-phase layer. A potential mechanism describing the formation process of this periodic-layered structure was proposed based on the diffusion kinetics based on the experimental results. [ABSTRACT FROM AUTHOR]

Polyaspartic acid (PASP) is a biodegradable green material with carboxyl groups (COOH) and amido groups (CONH). In the article, a novel urea‐formaldehyde (UF) resin modified by PASP and Ca‐montmorillonite (Ca‐Mt) was prepared by the alkaline‐acid‐alkaline method. The synthesized materials were characterized by X‐ray diffraction, Fourier transform‐infrared spectroscopy, thermal analysis (TG‐DTG), and scanning electron microscopy. The effects of viscosity, curing time, and free formaldehyde were investigated. The results showed that the layered structure of Ca‐Mt was exfoliated and dispersed in the bulk of UF. The thermal stability of the modified UF was much better than that of pure UF resin. The percentage of free formaldehyde was declined from 26 to 18%. Meanwhile, the UF composites showed the short curing time and the optimum viscosity. Finally, a synthetic process of UF modified by PASP and Ca‐Mt and a possible mechanism for immobilizing the free formaldehyde were suggested. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48038. [ABSTRACT FROM AUTHOR]

The mould foot roller is a key component of a continuous casting machine. In order to investigate the possibility of using laser cladding to repair mould foot roller, Fe-based powders and 42CrMo steel are used in this work. The laser cladding process parameters were optimized by orthogonal experiments. The chemical compositions, microstructure, properties of the cladding layer under the optimum process parameters, and substrate were systematically investigated by using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), microhardness test, wear test, and salt spray corrosion test. The results indicate that the primary factor affecting the width and depth of the cladding layer is laser power. The scanning speed also has a significant effect on the height of the cladding layer. The optimum process parameters for repairing the mould foot roller are 2 kW laser power, 4 mm/s scanning speed, and 15 g/min feeding rate of powder. Along the depth direction of the cladding layer, the microstructure of the coating gradually transforms from plane crystal, cell grains, or dendrites to equiaxed grains. The matrix is mainly martensite with retained austenite; the eutectic phase is composed of netlike M2B, particulate M23(C,B)6, and M7(C,B)3 phase. The hardness of the cladding layer is significantly improved, about three times that of the substrate. The weight loss of the cladding layer is just half that of the substrate. Its wear resistance and corrosion resistance have been significantly improved. The work period of the laser cladding-repaired foot roller is much longer than for the surfacing welding-repaired one. In summary, laser cladding technology can increase the life of mould foot rollers. [ABSTRACT FROM AUTHOR]

The improvement efficiency of a dredged slurry by vacuum preloading is greatly affected by the apparent clogging effect arising during the consolidation process, where the apparent clogging effect refers to the combined impacts of filter clogging and particle blinding around the drain due to particle migration and non-uniform consolidation. Three laboratory model tests with different types of soils were performed to investigate the apparent clogging effect. First, the filter clogging effect was investigated by scanning electron microscopy and cross-plane permeability tests. Second, changes in the particle size distribution due to particle migration were analysed at the micro- and macro-levels, and the particle migration induced blinding effect was assessed through the results of the compressibility and permeability tests. The test results indicated negligible particle migration in pure clay and relatively higher blinding effect in mixture soils. Finally, the effects of blinding due to particle migration and non-uniform consolidation on the overall consolidation rate were theoretically quantified. Both the analytical and tests results implied that the apparent clogging effect is predominantly by non-uniform consolidation rather than the particle migration-induced blinding effect, especially for cohesive marine clay. [ABSTRACT FROM AUTHOR]

This work reports the cyclic thermal shock behaviour of a Cr2AlC ceramic. The cyclic thermal shock tests were performed by quenching from 825 to 1325°C into ambient temperature water. The material withstood five thermal shock cycles without catastrophic thermal failure. The three-point bending test showed that its residual strength after five cycles of thermal shock decreased from 400MPa of the initial strength to about 68MPa as the quenching temperature rose to 1200°C, and then increased to ~80MPa after quenching from 1300°C. The microstructure of the quenched samples was characterised with scanning electron microscopy and optical microscopy. The main mechanism for the enhanced thermal shock resistance of Cr2AlC has been analysed. [ABSTRACT FROM AUTHOR]

Abstract: The paper reports on the preparation of the cleavable porous silicon (PSi) based hybrid material and application in pre-enrichment of trace heavy metal ions. The cleavable groups (benzimidazoledithio) were grafted on the PSi surface by a stepwise covalent process. PSi was first obtained by anodization of bulk silicon wafers and was subsequently silanized by 3-mercaptopropyltriethoxysilane (MPTS) to synthesize MPTS-PSi, the MPTS-PSi was further converted into pyridyldithio-terminated PSi (PDT-PSi), and finally, the PDT-PSi reacted with 2-mercaptobenzimidazole to form the benzimidazoledithio modified PSi (BDT-PSi). Scanning electron microscopy (SEM) was used to characterize the morphology of freshly prepared and modified PSi. Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy were performed to confirm the effectiveness of each step graft. According to the UV–vis spectra analysis, the disulfide linkage of BDT-PSi can be dissociated in presence of reduced glutathione (GSH). The pre-enrichment efficiency of BDT-PSi was investigated at the different pH for the different metal species (Cd, Hg, Pb, Cu and Co). The results show that the BDT-PSi possesses a similar preferential adsorption trend (Cd>Cu≫Hg∼Pb∼Co) at different pH (from 2.0 to 6.0). At pH 5.0, the best pre-enrichment efficiency for Cd ions is observed, the concentration of Cd is increased more than ten times and the recovery is found to be 95.4%. [Copyright &y& Elsevier]

• Stable isotope technique was firstly used to analyze ancient and artificial aged silk fabrics. • The stable isotope ratios of ancient silk fabrics under various excavation environments display different trends. • Heavy stable isotopes were enriched during degradation of the silk fabrics under most aging conditions. • Degradation of silk fabrics is a significant cause of stable isotope offset in historical silk fabrics. • Different aging factors should be considered when tracing the origin of historic silk fabrics using stable isotope techniques. Understanding the degradation of silk fibers and tracing silk fabrics from archeological sites have always been challenging. The stable isotope technique provides the possibility to trace ancient textiles, especially for the controversial issue of the silk origin. Chinese historic silk fabrics from the Xia dynasty (about 4000 years ago), Warring States period (B.C. 475- B.C. 221), Tang dynasty (A.D. 618- A.D. 907), Southern Song period (A.D. 1127- A.D. 1279), Ming dynasty (A.D. 1368- A.D.1644), and Qing dynasty (A.D. 1636- A.D. 1912) as well as some artificially aged silk specimens have been examined by scanning electron microscopy (SEM), attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, and isotope ratio mass spectrometry (IRMS) to investigate their degradation for traceability and preservation. It has been found that the surface morphology and secondary structure of silk were destroyed in the degradation process. Under most aging modes, the silk fabrics were enriched with heavy stable isotopes after degradation. In the case of charring, the isotopic ratios of heavy hydrogen and oxygen isotopes showed different variation tendencies, which need to be further studied for better understanding. The results revealed that stable isotope ratios of silk fabrics are affected by different aging conditions. The degradation of silk fabrics is an important cause of stable isotope offset in historical silk fabrics. Overall, this study provides useful insights into the silk degradation mechanism and can serve as a useful reference for tracing the rich textile heritage. [ABSTRACT FROM AUTHOR]

For the first time, a simple electrochemical co-deposition was utilized to synthesis the gold and zirconia nanocomposites modified graphene nanosheets on glassy carbon electrode (Au-ZrO 2 -GNs/GCE) for electrocatalytic analysis of methyl parathion (MP). According to Field-Emission Scanning Electron Microscopy (FE-SEM), Transmission Electronic Microscopy (TEM) and X-Ray Diffraction (XRD), the gold nanoparticles were uniformly distributed on the surface of graphene-based nanocomposite. The Au-ZrO 2 -GNs/GCE based sensor exhibited superior capacity for MP detection, ascribed to the strong affinity of zirconia towards the phosphoric group, as well as the high catalytic activity and good conductivity of Au-GNs. The best fabrication and work conditions were then obtained by systematically optimization of the electrodeposition process, pH value and enrichment time. Compared to the gold nanoparticles, zirconia or graphene modified electrodes, Au ZrO 2 -GNs/GCE sensor displayed superior electro-catalytic response toward MP oxidation. The sensor response current of square wave voltammetry was highly linearly correlated with the MP concentrations range of 1–100 ng mL−1 and 100–2400 ng mL−1 with the detection limit of 1 ng mL−1. The Au-ZrO 2 -GNs/GCE nanocomposite sensor showed excellent accuracy and reproducibility for detection of MP in Chinese cabbage samples, providing a new method for efficient pesticide detection in practical applications. Image 1 • Au ZrO 2 -GNs/GCE nanocomposite was synthesized via electrochemical co-deposition for the first time. • The nanocomposite was more sensitive for MP determination due to synergistic effect. • The sensor showed relatively wider linear range (1–100 ng mL−1 and 100–2400 ng mL−1). • The sensor can be practical application upon the excellent recovery results of Chinese cabbage. [ABSTRACT FROM AUTHOR]

Abstract Influencing factors on the preparation of high chromium white iron composites reinforced with in situ formed TiC x have been investigated. Various Ti 3 AlC 2 precursor powders with sizes from 6.5 to 75 μm were used to examine their influence on the dimension of in situ formed TiC x. Different heating rates and dwelling times were also adopted to study their effects on the microstructure of the composites. The initial Ti 3 AlC 2 precursor size has a minor influence on the grain size of in situ TiC x. However, the heating rate and the dwelling time have an impact on the distribution of TiC x in the matrix. The microstructure and phase composition of the prepared materials were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The nucleation and growth mechanism of TiC x in the composites has been discussed. Graphical abstract Image 1 Highlights • Influencing factors on the microstructure of high Cr white iron were investigated. • Ti 3 AlC 2 precursor size has a minor influence on the grain size of in situ TiC x. • Fine TiC x particles in composites can be obtained from even coarse Ti 3 AlC 2 powder. • Control of heating rate and dwelling time contributes to the distribution of TiC x. • This work offers a possibility to refine in situ high Cr white iron composites. [ABSTRACT FROM AUTHOR]

The corrosion behavior and products of bulk Fe 2 B in liquid Al at 750 °C were systematically investigated by static immersion tests, and characterized in detail through the joint approach of scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), electron probe micro-analyzer (EPMA), and transmission electron microscopy (TEM). The results indicate that the corrosion of Fe 2 B intermetallic in liquid Al is a diffusion-controlled process which involves the inter-diffusion of Fe and Al atoms at the solid-Fe 2 B/liquid-Al interface along with the formation of FeAl 3 intermetallics. The reactions between Fe 2 B and liquid Al results in a zigzag Fe 2 B/FeB two-phase transition region and a thick FeAl 3 intermetallic layer. The corrosion resistance of Fe 2 B against liquid Al can be attributed to the competition between the Fe 2 B/FeB phase transition, while the eventual corrosion results from micro-cracks developed from interfacial misfit, which enables spalling of the FeB and subsequent rapid corrosion of the matrix. Unlabelled Image • Fe-B alloy consisting of mainly Fe 2 B and traces of FeB boride were prepared. • The corrosion behavior of the Fe 2 B in liquid Al at 750 °C was revealed systematically. • The corrosion products at solid-Fe 2 B/liquid-Al interface were identified. [ABSTRACT FROM AUTHOR]

Abstract The co-continuous TiC x /Cu-Cu 4 Ti composites were prepared by infiltrating melting Cu into TiC 0.5 porous preforms. TiC 0.5 porous preforms were firstly synthesized by in-situ solid reaction process using powder Ti and carbon black as the starting materials, PVB as shaping and pore-forming agent. The prepared TiC 0.5 preforms showed 3D-connected visible pores characterized with two classes of sizes, i.e. intergranular pores with size of 10–30 µm and intracrystalline pores with 2–3 µm. Microstructure and phase compositions of the composites were detected by scanning electron microscopy (SEM) equipped with EDS and X-ray diffraction (XRD). Metal region of the composites contained Cu as well as a new phase Cu 4 Ti, which was formed by reaction of Cu and TiC 0.5. Composites prepared by this method had a compact structure and strong interface. Meanwhile, metal phase and ceramic phase maintained a co-continuous structure in three dimensions. Cu-Cu 4 Ti entered into the TiC x ceramic particles like root structure during the infiltration process. Flexural strength, fracture toughness and Vickers hardness of the composites reached 948.20 ± 124.04 MPa, 12.62 ± 0.37 MN m−3/2 and 606.4 ± 36.7 respectively when content of TiC x was 71.22 vol%. [ABSTRACT FROM AUTHOR]

Cr 2 AlC has excellent oxidation resistance, thermal shock resistance, and crack healability, making it a potential candidate for use in high temperature applications. So far work on the high temperature ablation properties of Cr 2 AlC has been less focused. This work firstly demonstrated the high temperature ablation behavior of Cr 2 AlC through the oxyacetylene torch testing. The linear and mass ablation rates were determined. The microstructure and the phase composition of the ablated samples were characterized with scanning electron microscopy and X-ray diffractometry. This work provided a basic understanding of the high temperature corrosion mechanism of Cr 2 AlC. [ABSTRACT FROM AUTHOR]

The research was focused on the execution of true triaxial compression tests and adopted acoustic emission (AE) and scanning electron microscopy (SEM). By doing so, the authors investigated the strength, deformation, AE, macroscopic and microscopic failure characteristics of Jinping marble in the 3-d stress space during brittle-ductile failure. The results showed that under true triaxial compression, when ductile failure occurs in Jinping marble, some ductile deformation remained in the samples, even after reaching peak strength. Post-peak ductility indicates Jinping marble with a certain post-peak carrying capacity, which has an important effect on rock failure. Moreover, the magnitude of the intermediate principal stress and the minimum principal stress affect the brittle-ductile transition and failure mechanism of Jinping marble. When the minimum principal stress is small, rocks present brittle failure and split to an extent that mainly depends on tensile failure, and the brittle-ductile transition of rocks is only slightly influenced by the intermediate principal stress. Under large minimum principal stress conditions, the rock behavior gradually turns from ductile to brittle failure with increasing intermediate principal stress. When the minimum principal stress is large and the intermediate principal stress is small, rocks exhibit ductile failure (mostly shown as shear failure). Besides, when the minimum principal stress is large and the difference between minimum and intermediate principal stress is larger, brittle failure occurs along tensile-shear fractures. [ABSTRACT FROM AUTHOR]

High chromium white irons have excellent abrasion resistance due to the presence of hard eutectic M 7 C 3 (M = Fe, Cr) carbides in a ferrous matrix. However, the appearance of large and coarse M 7 C 3 carbides is detrimental to the performance of high chromium white irons. To modify the microstructure, in situ decomposition of Ti 3 AlC 2 to TiC x which is expected to inhibit the growth of M 7 C 3 in a high chromium white iron has been adopted in the present study. The in situ formed TiC x effectively refined the M 7 C 3 carbide structure. The influences of Ti 3 AlC 2 content, sintering temperature and heating rate on the microstructural evolution of high chromium white iron were investigated. Influencing factors on the size and dispersion of the TiC x grains in the ferrous matrix have been analyzed. A modified microstructure with a fine eutectic M 7 C 3 structure and a homogenous distribution of small round TiC x can be achieved by optimization of temperature and dwell time. X-ray diffraction, differential scanning calorimetry and scanning electron microscopy were used to investigate phase composition, phase transition and microstructure of materials. [ABSTRACT FROM AUTHOR]

A relatively large number of pH-sensitive minerals (e.g., calcite, dolomite, siderite) and redox-sensitive compositions (e.g., organic matter, siderite, pyrite, and chlorite) are present in gas-bearing shale formations. During hydraulic fracturing, some of these compositions can be dissolved under acidic or oxic condition and may generate critical transport pathways to bypass water blockage within the fracture-matrix interface. This paper reports the effects of 5% HCl or 15% H 2 O 2 reactive fluids on transport pathway and methane diffusion capacity of Longmaxi shale samples. Experiments show that these sensitive minerals are distributed evenly throughout the shale matrix as dispersed or isolated grains. Reactivity differences between sensitive compositions and non-sensitive minerals cause heterogeneous dissolution at micrometer scale and generate substantial new pore space in the reaction zones, giving an overall pore volume increase by 4.6–6.6 vol % calculated using μCT data. Apart from dissolution pores, many oxidation-related microfractures with a spacing less than 10 μm are also observed in H 2 O 2 -treated shale. Due to resolution limitations of SEM and μCT imaging, these new transport pathways appearing as separated void spaces are actually connected by much smaller pores at nanoscale, leading to a greater than 3.7-fold increase in macropore diffusivity. Despite more water imbibition into the H 2 O 2 -treated shales, the largest increase in diffusivity is also observed post oxidizing treatment. Our study clearly demonstrates that the newly formed transport pathways can reduce the diffusion pathway length and tortuosity of nanopore systems, thereby significantly improving wet shales' diffusivity. These observed changes in transport pathway and diffusivity indicate that acidizing or oxidizing treatment may be a possible method for mitigating water blockage within fracture-matrix interface of hydraulically fractured Longmaxi shale gas formation. • Heterogeneous dissolution in Longmaxi shale occurs after 5% HCl acidizing or 15% H 2 O 2 oxidizing treatment. • The newly formed pores and dense microfractures can generate well-interconnected transport pathways, leading to a greater than 3.7-fold increase in macropore diffusivity. • The newly formed transport pathways have a great potential for mitigating water blockage within fracture-matrix interface. [ABSTRACT FROM AUTHOR]

Abstract: A high purity of Ti3AlC2 powder has been synthesized by pressureless sintering a mixture of Ti/Al/TiC/Sn (Sn as a sintering additive) powders with a mole ratio of 1:1:1:0.1 in the temperature range of 1350–1500°C for 10min in an Ar atmosphere. Sn is an effective additive and its effect on the formation of Ti3AlC2 has been discussed. The formation mechanism of Ti3AlC2 has been proposed. X-ray diffraction analysis and scanning electron microscopy were used to characterize the samples. [Copyright &y& Elsevier]

Abstract: The reaction mechanism for the formation of Ti2SnC has been investigated. A mixture of Ti5Sn3 and TiC powders was adopted to synthesize Ti2SnC. It confirms that Ti2SnC forms from the reaction of Ti5Sn3 and TiC. Scanning electron microscopy, differential scanning calorimetry and X-ray diffraction were used to analyze the reaction mechanism. [Copyright &y& Elsevier]

Abstract: Solid solution Ti3SiAl0.2C1.8 was synthesized by sintering powder compacts containing Ti, Si, Al, and C with a mole ratio of 3:1:0.2:1.8 at 1550°C for 5min in Ar. X-ray diffraction and scanning electron microscopy were used to characterize the samples. The results show that nearly single solid solution was obtained except for the presence of a small amount of TiC. The observation from the fracture surface shows that delamination, kink band formation and crack deflection are prevalent features in the deformed Ti3SiAl0.2C1.8 grains. The crystal parameters for Ti3SiAl0.2C1.8 were analyzed and the multiple energy dissipation mechanisms were discussed. [Copyright &y& Elsevier]

• Monodisperse core–shell silica particles are formed by continuous self-assembly. • The in situ silica sol-gel method can be easily scaled up for production. • Excellent column performance for HPLC separation. In recent years, core–shell silica particles (CSSPs) have been increasingly used for highly efficient separation at fast flow rates and relatively low back pressures in high-performance liquid chromatography (HPLC). However, material synthesis techniques for producing CSSPs economically in batch processes remain elusive. In this report, a practical and straightforward method for the preparation of CSSPs is presented. By refluxing freshly prepared nonporous silica particles in ammonia–water solution in the presence of poly(diallyldimethylammonium chloride) at 70–100 °C, CSSPs with shell thicknesses of up to 300 nm and pore sizes from 8 to 25 nm were easily prepared. The effects of the synthetic conditions on the shell thickness, surface area, and pore size were investigated in detail, and the method reproducibility was evaluated in scale-up experiments. A mechanism of CSSP formation is also proposed. The CSSPs were characterized via scanning electron microscopy, transmission electron microscopy, laser particle size (dynamic light scattering) analysis, and nitrogen adsorption and desorption experiments. The synthesized 3.4-μm CSSPs were functionalized with dimethyloctadecylchlorosilane and used as an HPLC packing material, exhibiting excellent separation performance for both small molecules and large biomolecules. In summary, we report the simplest method developed thus far for the preparation of monodisperse core–shell silica particles suitable for HPLC column packing. [ABSTRACT FROM AUTHOR]

Mo-Si-B alloys suffer from the materials disintegration below 800 °C due to the formation of a porous oxide scale and the evaporation of MoO 3 , known as Mo pesting. The nanolaminated ternary boride compound of MoAlB contains both Mo and B elements, hence, pesting is expected at temperatures below 800 °C as in Mo-Si-B alloys. However, the oxidation behavior of MoAlB at moderate temperatures has been less studied so far. This work reports on the cyclic oxidation behavior of MoAlB in air in the temperature range 450–850 °C over a time of up to 100 h. The results showed an excellent oxidation resistance of MoAlB at temperatures of 750 °C and 850 °C due to the formation of a dense and continuous Al 2 O 3 scale, which acts as a barrier layer preventing oxygen inward diffusion and the evaporation of MoO 3 and B 2 O 3 oxides. No pesting was found in the MoAlB material during oxidation at temperatures below 850 °C. The phase composition and microstructure of the oxidized samples were characterized by x-ray diffraction and scanning electron microscopy techniques. Image 1 • Cyclic oxidation behavior of MoAlB in air at 450 °C to 850 °C for 100 h was performed. • A dense Al 2 O 3 scale was formed after oxidation at 750 °C and 850 °C for 100 h. • The Al 2 O 3 scale protects MoAlB from oxidation and prevents the evaporation of oxides. • No "Mo pesting" was found in MoAlB as in Mo-Si-B alloys upon oxidation below 800 °C. [ABSTRACT FROM AUTHOR]

The MAB phase MoAlB has attractive properties both at room and high temperatures. To further improve its properties, a possible way is to form solid solutions by partially substituting one of constituting elements in MoAlB. This work reports on the synthesis of MoAl 1-x Si x B solid solutions by powder metallurgy. Influences of sintering temperature, dwelling time, and composition of starting mixture on the solubility limit of Si in MoAlB have been investigated. The maximum solubility of Si was 0.91 at.%, corresponding to x = 0.03. Increase of Si content in the starting mixtures caused the formation of other competing phases. Phase composition and microstructure were characterized by x-ray diffraction method and scanning electron microscopy. A dense MoAl 0·97 Si 0·03 B solid solution has been achieved by hot-pressing a MoB/1.3Al/0.1Si mixture at 1200 °C with 25 MPa for 1 h, and its mechanical properties have been measured. An increase in strength and hardness is achieved by solid-solution strengthening. The flexural strength and the hardness of the solid solution are higher than those of MoAlB, viz. 385 MPa vs 307 MPa, and 14.89 GPa vs 8.43 GPa. Image 1 • MoAl 1-x Si x B solid solutions have been achieved. • Influencing factors on the synthesis of solid soltions have been determined. • The maximum solubility of Si in MoAlB was 0.91 at.%. • Optimization of processing conditions produces a single solid solution. • An increase in strength and hardness is achieved by solid-solution strengthening. [ABSTRACT FROM AUTHOR]